Rationally Design a Sulfur Cathode with Solid-Phase Conversion Mechanism for High Cycle-Stable Li–S Batteries

Solid–solid reactions are very effective for solving the main challenges of lithium–sulfur (Li–S) batteries, such as the shuttle effect of polysulfides and the high dependence of electrolyte consumption. However, the low sulfur content and sluggish redox kinetics of such cathodes dramatically limit the practical energy density of Li–S batteries. Here a rationally designed hierarchical cathode to simultaneously solve above-mentioned challenges is reported. With nanoscale sulfur as the core, selenium-doped sulfurized polyacrylonitrile (PAN/S₇Se) as the shell and micron-scale secondary particle morphology, the proposed cathode realizes excellent solid–solid reaction kinetics in a commercial carbonate electrolyte under high active species loading and a relatively low electrolyte/sulfur ratio. Such an approach provides a promising solution toward practical lithium sulfur batteries.